Using DNA Nanostars to Program the Crystallization of DNA-Coated Colloids

DNA-coated colloids have been used as a model system to study self-assembly, and in particular, crystallization: the formation of ordered, repeating structures. Typically, attractive interactions between particles are mediated by hybridization between DNA strands grafted onto the particles’ surfaces. In this talk, I will describe a new approach in which DNA nanostars control the interactions of DNA-coated colloids. DNA nanostars are multi-armed, self-assembled structures made up of complementary single-stranded DNA molecules. Changing the number of strands and their sequences alters the number of arms, arm length, and strength of interaction. We find that two-, four-, and eight-arm nanostars can direct the assembly of colloidal crystals with variable lattice spacing. Furthermore, whereas direct hybridization typically results in defective crystals in a one-component mixture, we find that four-arm nanostars form single-domain, faceted crystals, which we hypothesize results from changes in the crystal growth velocity and surface energies. These results suggest that DNA nanostars may be a useful tool to more easily control single crystal formation and program crystal properties, like the lattice spacing, without the need to synthesize many different particle types.